1. Field of the Invention
The present invention relates to a structure of a pluggable optical transceiver, in particular, the invention relates to a new structure of the transceiver which enables to reduce the cost of the production thereof.
2. Related Prior Art
The pluggable optical transceiver (hereinafter denoted as transceiver) is installed on the host system such that a cage, which is made of metal and has a box shape with one end being opened and protruded from the face panel of the host system, receives the transceiver in the open end thereof to expose the optical receptacle provided in the front end of the transceiver from the face panel of the host system. The optical receptacle receives an optical connector accompanied with an optical fiber. Thus, the optical fiber may optically couple with an optical device installed within the transceiver and establish the optical communication between the fiber and the optical device.
The cage provides an electrical connector in the deep end thereof, while the transceiver provides, in a rear end thereof, an electrical plug to mate with the electrical connector in the cage. By inserting the transceiver into the cage, the electrical plug of the transceiver comes to mate with the electrical connector, which enables the transceiver to communicate with the host system, namely, exchanging the electrical information and supplying the electrical power from the host system to the transceiver. Moreover, by setting the electrode of the plug in a preset configuration, the transceiver can be optionally inserted into or removed from the cage as the host system is powered on, which is the so-called hot-pluggable function.
One type of such pluggable transceiver has been specified in a multi-source agreement (MSA) as “Small Form-Factor Pluggable (SFP) Transceiver Multi Source Agreement” published through the internet <http://www.shelto.com/SFP/SFP MSA.pdf>. However, this MSA merely specifies the fundamental electrical specification, the pin-assigning, and the physical dimensions, rules no substantial architecture. The MSA only ensures that, as long as the transceiver satisfies the agreement, the transceiver can be installed within the cage and show the fundamental performance. Recently, the optical communication may be available in personal, namely, the optical fiber is brought to the independent home, and an optical transceiver that satisfies the agreement with the cost thereof further reduced has been requested.
The optical transceiver is roughly comprised of, an optical subassembly (hereinafter denoted as OSA) that communicates with the optical fiber and converts the optical signal into the electrical signal, or the electrical signal into the optical signal; an electronic circuit for processing the electrical signal and a substrate for installing the circuit thereon; a chassis for installing the OSA and the substrate thereon; and a cover for protecting the OSA, the substrate and the chassis.
The United States patent, U.S. Pat. No. 6,335,869, has disclosed an optical transceiver, in which the substrate is assembled with the resin made chassis only by fitting. The metal cover surrounds the chassis that fixes the OSA with a fixing member. Although the resin made chassis reduces the cost or the price of the transceiver, the heat dissipating function for components installed on the substrate might have disadvantages because the resin made chassis fixes the substrate so as to wrap the substrate. Moreover, the width of the chassis limits the width of the substrate, which also limits the area where the components may be mounted. The fixing member increases the number of components which increases the cost not only in the components themselves but also the assembly thereof.
Another United States patent, U.S. Pat. No. 6,439,918, has disclosed another configuration of the transceiver, in which the metal chassis fixes the substrate with screws. Although not restricted to the metal chassis in this configuration, the chassis is preferable to be made of metal from the viewpoint of the heat conduction. The metal chassis is inevitable to fix the substrate with screws. Moreover, the chassis includes two portions, one of which is for the optical receptacle and the other is for mounting the substrate, formed by die-casting in one body. However, the die-casting requires the post processing for protecting the die-cast metal from deteriorating, which may increase the process cost.
Thus, the conventional transceiver is inconsistent in the heat dissipating function and the production cost. The transceiver, whose dimensions are ruled by the agreement, is also inconsistent in the area capable of mounting the components and simplifying the manufacturing. Therefore, the optical transceiver according to the present invention enables to maintain the heat dissipating function and the area for mounting the components with the manufacturing thereof simpler, accordingly the cost thereof becomes lower, than the conventional transceiver.